NEW ARGININE-REQUIRING MUTANTS IN CHLAMYDOMONAS-REINHARDTII

Twelve arginine-requiring mutants of the unicellular green alga Chlamydomonas reinhardtii previously isolated in our laboratory were investigated to find new blocks in the biosynthetic pathway of arginine. In addition to the already described mutants lacking acetylglutamyl phosphate reductase (arg 1), ornithine carbamoyltransferase (arg 4) and argininosuccinate lyase (arg 7), three new types of mutants were found lacking acetylornithine aminotransferase (arg9-1, arg9-2), acetylornithine glutamate transacetylase (arg 10) and argininosuccinate synthetase (arg8-1, arg8-2, arg8-3) respectively. The genetic analysis of these new mutants showed that arg9 and arg8 are unlinked to the other arginine markers and that arg10 probably carries a chromosomal mutation inducing a very high lethality of meiotic products.